The average Anthropomorphic Duck resembles the most well-known (out-of-universe) specimen, Donald Fauntleroy Duck. They are much smaller than most other species (around 3 foot tall) and is covered with very thin but also very covering feathers (even on his face and hands), which are usually but not always white. The feathers of the tail are slightly longer, as are those on the head, which tend to stick up just like short uncombed hair. They have huge eyes that touch the beak, above which the muscles of the face can form apparent eyebrows, though there is usually no hair to mark their shape. The beak is of a light orange color and contains a narrow, dark pink tongue which is pointed at the end, as well as numerous flat teeth that are mostly hidden. The beak appears to be made of very flexible cartilage, allowing them to talk and to move their "lips" to form specific faces (such as a smile). They have short and narrow orange legs which continue into wide and very flat webbed feet; they are even more flexible than the beak and, in spite of the identical color, are more likely an odd-colored flesh than cartilage. They have human-like arms at the end of which are human-looking, albeit four-fingered, hands.
Most ducks are born with relatively small eyes that do not touch the beak (as seen with Huey, Dewey and Louie); the eyes grow to touch the beak (possibly) around the time of puberty. There is however a mutation that leads to the eyes remaining small even in adulthood (as is the case of Matilda McDuck). This may be a trait that can be, but is not always, hereditary, as Matilda's mother, Downy O'Drake, has these eyes, but her other two children don't.
Cross-breeding with Other Birds
Anthropomorphic ducks can (and often do) crossbreed with other anthropomorphic birds, such as geese (see Daphne Duck and Goosetave Gander), loons (see Eider Duck and Lulubelle Loon) and coots (see Elvira Coot and Humperdink Duck). The results are negligible; the main changing factors are the shape of beak (which can become more pointy and angular) and the "small-eyes" character, which often results from crossbreeding with geese.
Cross-breeding with Mammals
It is known that anthropomorphic duck can successfully crossbreed with Humans and Dognoses. This leads to some specimens (depending on the level of mammal genome in them) displaying human (or dognose) characteristics. The less obvious consequence is some ducks beginning to grow hair (not just feathers shaped like hair, like Scrooge McDuck's whiskers), a good example being Della Duck. More conspicuously, female ducks may have breasts; even more strikingly, many ducks stand as tall as humans and have human-shaped legs (albeit covered with feathers) instead of the short orange legs and webbed feet. Carl Barks occasionally jokingly referred to these "human-like" ducks as "waterfowloids".